This invention relates in general to digital representation of data and more specifically to a system for increasing the range of representable values in waveforms.
Digital processing is used advantageously in many aspects of signal processing including audio, image, radio-frequency, infrared, math functions, etc. A signal is typically captured to the digital domain by analog-to-digital conversion of a physical signal to a digital waveform representation. Once the physical signal has been captured digitally, it can be modified, manipulated, copied, transferred, etc., with little or no degradation to the waveform and with many advantages provided by digital processing.
However, a problem arises with traditional approaches to digital waveform representation. Typically, the waveform is represented by a large number of “samples.” Each sample is a digital value (usually binary) and is represented by a digital “word” that is a fixed number of bits in width. The number of bits in a word dictates the possible range of values that can be represented in a sample corresponding to the word. If the sample needs a value that is larger than can be represented by a word then the waveform can not be accurately represented and a condition known as “clipping” occurs.
When an audio signal is digitally clipped, the waveform representation no longer is a true representation of the desired audio signal. Instead, the sample values are represented by the closest value allowed by the word width in a processing system. Typically, this means that the word values are at their highest maximum positive or negative magnitudes for the duration of the signal extending beyond the representable values of the sample size. The range of values that can be handled by a processing system is referred to as the “dynamic range” or “bit width,” “word width,” etc., of the system.
Since different systems may have different dynamic ranges, the clipping effect may make it undesirable, or impossible, for different systems to work together or to exchange data. Increasing the dynamic range of a system is often not possible after the system has been manufactured. The production of systems with larger dynamic range is more expensive and often more difficult since more processing power, larger buses, higher performance and wider memory, and improvements in other resources must be included in the systems.